Tugarinov Vitali, Kay Lewis E
Protein Engineering Network Centres of Excellence and the Department of Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
J Biomol NMR. 2004 Jul;29(3):369-76. doi: 10.1023/B:JNMR.0000032562.07475.7f.
Relaxation in methyl groups is strongly influenced by cross-correlated interactions involving the methyl dipoles. One of the major interference effects results from intra-methyl (1)H-(13)C, (1)H-(1)H dipolar interactions, leading to significant differences in the relaxation of certain multiplet components that contribute to double- and zero-quantum (1)H-(13)C spectra. NMR experiments are presented for the measurement of this differential relaxation effect. It is shown that this difference in relaxation between double- and zero-quantum multiplet components can be used as a sensitive reporter of side chain dynamics and that accurate methyl axis order parameters can be measured in proteins that tumble with correlation times greater than approximately 5 ns.
甲基的弛豫受到涉及甲基偶极子的交叉相关相互作用的强烈影响。主要干扰效应之一源于甲基内的（1）H-（13）C、（1）H-（1）H偶极相互作用，导致某些多重峰组分的弛豫存在显著差异，这些差异对双量子和零量子（1）H-（13）C谱有贡献。本文介绍了用于测量这种微分弛豫效应的核磁共振实验。结果表明，双量子和零量子多重峰组分之间的弛豫差异可作为侧链动力学的灵敏报告指标，并且在相关时间大于约5纳秒翻滚的蛋白质中可以测量到准确的甲基轴序参数。
